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Numerical evidence for thermally induced monopoles

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Fijan, D 
Lightwood, RA 
Šarić, A 
Dellago, C 


Electric charges are conserved. The same would be expected to hold for magnetic charges, yet magnetic monopoles have never been observed. It is therefore surprising that the laws of nonequilibrium thermodynamics, combined with Maxwell's equations, suggest that colloidal particles heated or cooled in certain polar or paramagnetic solvents may behave as if they carry an electric/magnetic charge. Here, we present numerical simulations that show that the field distribution around a pair of such heated/cooled colloidal particles agrees quantitatively with the theoretical predictions for a pair of oppositely charged electric or magnetic monopoles. However, in other respects, the nonequilibrium colloidal particles do not behave as monopoles: They cannot be moved by a homogeneous applied field. The numerical evidence for the monopole-like fields around heated/cooled colloidal particles is crucial because the experimental and numerical determination of forces between such colloidal particles would be complicated by the presence of other effects, such as thermophoresis.



colloids, molecular simulation, monopoles, nonequilibrium thermodynamics, soft matter

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Proceedings of the National Academy of Sciences of the United States of America

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National Academy of Sciences
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (674979)
We acknowledge financial support from the Austrian Academy of Sciences through a doctoral (DOC) fellowship (to P.W.), the Austrian Science Fund (FWF) within the Spezialforschungsbereich Vienna Computational Materials Laboratory (Project F41) (C.D.), and the European Union Early Training Network NANOTRANS (Grant 674979 to D. Frenkel). The results presented here have been achieved in part using the Vienna Scientific Cluster.
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